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// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/prctl.h>
#include <linux/sched.h>
#include <asm/cpu_has_feature.h>
#include <asm/cputable.h>
#include <asm/processor.h>
#include <asm/reg.h>
static int __init init_task_dexcr(void)
{
if (!early_cpu_has_feature(CPU_FTR_ARCH_31))
return 0;
current->thread.dexcr_onexec = mfspr(SPRN_DEXCR);
return 0;
}
early_initcall(init_task_dexcr)
/* Allow thread local configuration of these by default */
#define DEXCR_PRCTL_EDITABLE ( \
DEXCR_PR_IBRTPD | \
DEXCR_PR_SRAPD | \
DEXCR_PR_NPHIE)
static int prctl_to_aspect(unsigned long which, unsigned int *aspect)
{
switch (which) {
case PR_PPC_DEXCR_SBHE:
*aspect = DEXCR_PR_SBHE;
break;
case PR_PPC_DEXCR_IBRTPD:
*aspect = DEXCR_PR_IBRTPD;
break;
case PR_PPC_DEXCR_SRAPD:
*aspect = DEXCR_PR_SRAPD;
break;
case PR_PPC_DEXCR_NPHIE:
*aspect = DEXCR_PR_NPHIE;
break;
default:
return -ENODEV;
}
return 0;
}
int get_dexcr_prctl(struct task_struct *task, unsigned long which)
{
unsigned int aspect;
int ret;
ret = prctl_to_aspect(which, &aspect);
if (ret)
return ret;
if (aspect & DEXCR_PRCTL_EDITABLE)
ret |= PR_PPC_DEXCR_CTRL_EDITABLE;
if (aspect & mfspr(SPRN_DEXCR))
ret |= PR_PPC_DEXCR_CTRL_SET;
else
ret |= PR_PPC_DEXCR_CTRL_CLEAR;
if (aspect & task->thread.dexcr_onexec)
ret |= PR_PPC_DEXCR_CTRL_SET_ONEXEC;
else
ret |= PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC;
return ret;
}
int set_dexcr_prctl(struct task_struct *task, unsigned long which, unsigned long ctrl)
{
unsigned long dexcr;
unsigned int aspect;
int err = 0;
err = prctl_to_aspect(which, &aspect);
if (err)
return err;
if (!(aspect & DEXCR_PRCTL_EDITABLE))
return -EPERM;
if (ctrl & ~PR_PPC_DEXCR_CTRL_MASK)
return -EINVAL;
if (ctrl & PR_PPC_DEXCR_CTRL_SET && ctrl & PR_PPC_DEXCR_CTRL_CLEAR)
return -EINVAL;
if (ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC && ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC)
return -EINVAL;
/*
* We do not want an unprivileged process being able to disable
* a setuid process's hash check instructions
*/
if (aspect == DEXCR_PR_NPHIE &&
ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
dexcr = mfspr(SPRN_DEXCR);
if (ctrl & PR_PPC_DEXCR_CTRL_SET)
dexcr |= aspect;
else if (ctrl & PR_PPC_DEXCR_CTRL_CLEAR)
dexcr &= ~aspect;
if (ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC)
task->thread.dexcr_onexec |= aspect;
else if (ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC)
task->thread.dexcr_onexec &= ~aspect;
mtspr(SPRN_DEXCR, dexcr);
return 0;
}
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